<!DOCTYPE html>
<html lang="zh-CN">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>

<style>
    .box {
        display: flex;
        flex-direction: row;
        flex-wrap: wrap;
        align-content: space-around;
        width: 800px;
        height: 400px;
        margin: 0 auto;
        background-color: pink;
    }

    .box div {
        width: 100px;
        height: 100px;
        background-color: green;
        border: 1px solid red;
    }

    .box .first {
        flex-basis: 200px;
    }
</style>

<body>


<div class="box">
    <div class="first">1</div>
    <div class="second">2</div>
    <div class="third">3</div>
    <div class="third">4</div>
    <div class="third">5</div>
    <div class="third">6</div>
    <div class="third">7</div>
    <div class="third">8</div>
    <div class="third">9</div>
    <div class="third">10</div>
    <div class="third">11</div>
    <div class="third">12</div>
</div>

</body>
</html>